Every football injury is subjective and dependent on the player. Medical professionals have found, through years of study and practice, that it takes four-to-six weeks, on average, for this kind of injury to be fully healed. You do have to listen to the player, but you also have to listen to people who know what they're talking about.
I just hope Burkhead understands that if he tries to come back before he's really ready, he could drastically damage his team's season. As it stands right now the injury isn't a big deal, but it could become one if he isn't careful. Being on the field isn't always what's best for the team. Properly healing is sometimes more valuable.